The barrel/magtube yoke might be gummed up and tight. I haven't seen one where the barrel would rotate (counterclockwise looking from the muzzle) until the crosspin is pushed down to extend below the magtube. In fact the crosspin is designed as a lever to turn the magtube as well as a preventer against doing so. Overzealous pushing on the slide can move the yoke forward on the barrel. If this happens, you should see dragmarks in the bluing on the barrel. I didn't know the screw in the yoke did anything more than anchor the yoke in one position. There is a screw in a notch in the adjustment sleeve that has the interrupted thread which engages similar in the receiver but you shouldn't have to play with that for the first hundred years.
jack
